Gaseous discharge display panel including pilot electrodes and radioactive wire

ABSTRACT

In a plasma display panel consisting of gas enclosed between adjacent insulating members, a light source is used to supply charged particles in the gas to permit firing of the gas when coordinate conductors identifying a site location are energized. The use of such pilot lamps facilitates ignition in firing with uniform selection and firing potentials within all sites of the display panel. To eliminate the difficulty in achieving firing during cold starts a radioactive source comprised of a copper wire electroplated with nickel 63 and overcoated with a protective coat of nickel is placed within the gas panel to provide a source of free electrons. The wire is held in place by friction against the inside walls of the panel. Since the wire emits only beta radiation, no radiation hazard exists externally to the panel.

United States Patent [1 1 Edwards et al. Dec. 23, 1975 GASEOUS DISCHARGE DISPLAY PANEL 3,609,658 9/1971 Soltan 313/188 x INCLUDING PILOT ELECTRODES AND 3,684,909 8/1972 Caras 313/54 RADIOACTIVE WIRE Filed:

Assignee:

Inventors: Roger Joseph Edwards, Woodstock;

Barouyr Zareh Hairabedian, Lake Katrine; Neil Myron Poley, Kingston, all of NY.

International Business Machines Corporation, Armonk, NY.

Sept. 3, 1974 Appl. No.: 502,268

US. Cl. 313/54; 313/188; 313/198;

Int. Cl. HOIJ 17/32; H01J 61/54 Field of Search 313/54, 188, 198, 201;

References Cited UNITED STATES PATENTS Rentschler Wellinger et al. 313/54 Ohmart 313/54 X Baker et a1. 313/188 X Primary Examiner-Palmer C. Demeo Attorney, Agent, or Firm-C. E. Rohrer; W. N Barret, Jr.

[57] ABSTRACT In a plasma display panel consisting of gas enclosed between adjacent insulating members, a light source is used to supply charged particles in the gas to permit firing of the gas when coordinate conductors identifying a site location are energized. The use of such pilot lamps facilitates ignition in firing with uniform selection and firing potentials within all sites of the display panel. To eliminate the difficulty in achieving firing during cold starts a radioactive source comprised of a copper wire electroplated with nickel 63 and overcoated with a protective coat of nickel is placed within the gas panel to provide a source of free electrons. The wire is held in place by friction against the inside walls of the panel. Since the wire emits only beta radiation, no radiation hazard exists externally to the panel.

4 Claims, 3 Drawing Figures US. Patent Dec. 23, 1975 FIG! FIG.

FIG.3

GASEOUS DISCHARGE DISPLAY PANEL INCLUDING PILOT ELECTRODES AND RADIOACTIVE WIRE BACKGROUND OF THE INVENTION 1. Field of the Invention 1 The invention relates to plasma display devices and more particularly to an improved means for firing the gas within said device.

2. Description of the Prior Art 7 I The use of a light source as a pilot light for gas cells within a plasma display device is well known and is shown in US. Pat. No. 3,609,658 Pilot Gas Cells For Gas. Panels Parviz Soltan, Sept. 28, 1971. The device disclosed in the Soltan patent employs a light source incident to the panel for the purpose of establishing a source of metastables, electrons and ions to permit uniform ignition within the panel cells. It utilizes auxiliary pairs of electrodes having an independent power supply which when discharged provides and maintains the light source. The gas panel has an inherent starting problem after it has not been ignited for a day or more. Furthermore, under normal lighting, photon and cosmic rays provide sufficient ionnization to fire the initial discharge by use of the pilot light. However, in the dark this process is attenuated sufficiently that cold starting is difficult.

Ultra-violet excitation or high voltage can be used to generate the free electrons necessary to allow ignition of the panel. This technique is not acceptable in a commercial product because of high cost and low reliabillty.

It is, therefore, an object of this invention to provide an inexpensive and reliable means of cold start ignition in a plasma display panel.

It is a further object of this invention to provide the proper quantity, form, material and placement of a radioactive source to provide a cold start within a gas panel with a minimum of hazard from stray radiation.

The above objects are accomplished in accordance with the' invention by providing a radioactive source in the form of a copper wire electroplated with nickel 63 and overcoated with a protective coat of nickel. The wire is placed near the pilot lamp and emits beta radiation sufficient to facilitate initial firing of the pilot light when a drive signal is applied thereto.

The invention has the advantage that it assures a cold start within a short time. It has the further advantage that it is less costly than electronic start and more reliable.

The use of a small plated wire has the advantage that the wire can be introduced into the panel without changes in the manufacturing process.

Another advantage of the invention is that the radioactive wire is superior to radioactive gas utilized in the prior art because of the smaller concentrations which are necessary to achieve the same result. The wire will not contaminate the gas panel gas and there is no danger of radioactive leakage.

Furthermore, the nickel 63 in the form of a wire requires a lower quantity of radioactivity than a radioactive gas. Since nickel 63 is a weak beta emitter no radioactivity is present outside the gas panel.

Finally, the invention has the advantage that the use of friction to secure the nickel 63 wire to the sides of the gas panel chamber minimizes the manufacturing steps.

BRIEF DESCRIPTION OF THE DRAWINGS 5 ing more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawing:

FIG. 1 is a top view illustration of the preferred embodiment of the. invention;

FIG. 2 is aside view of the embodiment shown in FIG. I and FIG. 3 is a detailed view of the nickel plated wire shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2 the gas panel structure is shown. Details which are not essential to the present invention have been omitted but may be ascertainedfrom'US. Pat. No. 3,609,658 cited above and from the articles and patents referred to in the text of said patent. I

Transparent insulating members 10 and 12 (FIG. 2) comprise opposite sides of a glass enclosed chamber. These sides have printed on them parallel orthoginal drive lines 14 and 16 (FIG. I). The members are sandwiched together such that the parallel lines 14 and I6 lie perpendicular to each other resulting in sites or celis at the intersection 18.

In addition to the above electrodes, there are printed pilot electrodes 20 and 22. The pilot electrodes intersect so as to form a pilot cell 24 at the intersection. The pilot cell is placed in close proximity to the display cells to provide a source of charged particles. A gaseous mixture is injected into the chamber during the manufacturing process by means of tube assembly 26 which in FIG. 2 has been shown to be sealed and capped. The pilot electrode pairs 20, 22 are connected to appropriate drivers which are not shown. This means that the pilot lamps may be continuously ignited to maintain conditioning which permits instantaneous operation of the display device.

Refer now to FIG. 3 which is an enlargement of a section of the gas panel taken at the pilot lamp electrodes 20 and 22 shown in FIG. 2. In FIG. 3, the insulating panels 10 and 12 are shown with electrodes 20 and 22 electroplated thereon. To protect the electrodes, the insulating panels 10 and 12 are covered with a further insulating layer 25 and 27.

A small L-shaped radioactive wire 28 is shown between the insulating layers and placed near the pilot lamp to supply a source of free electron. The diameter of the wire is smaller than the distance between the insulating members 10 and 12. Each leg of the .wire has a slight spring to it so that it is held in place between the layers by spring tension.

The wire consists of oxygen-free high conductivity annealed copper wire electroplated with nickel 63 (radioactive strength of l i 0.1 microcurie per centime- 'ter) and overcoated with nickel 2500 i 500 angstroms thick.

In summary, a gas panel has been shown which consists of a gaseous discharge medium sealed within a chamber which is enclosed by two flat insulating mem bers which form the walls of the chamber. A pair of pilot electrodes is provided, one electrode deposited on one of said panels and the other electrode deposited on the other panel. A radioactive wire is placed in the 3 chamber within the vicinity of the electrodes for providing a source of free electrons for conditioning the gas panel for firing. The wire has a slight spring to it so that when it is placed within the chamber the wire is held in place between the walls of the chamber by friction.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

l. in a plasma display device comprising a panel with an illuminable gas sealed in a chamber between two substantially transparent flat plates, said chamber containing a multiplicity of light emitting cells wherein each cell is formed at a crossover point of spaced orthogonal conductors, such that the gas in the region of each coordinate intersection of said conductors may be tired in response to a firing potential difference applied to said orthogonal conductors, the improvement comprising 4 a pair of pilot electrodes one of which is disposed on the interior surface of one of said flat plates, the other of which is placed on the interior surface of the other of said flat plates, and

a radioactive wire located within the chamber between the pilot electrodes,

whereby the radiation from said wire aids the ionization of gas in the region of said pilot electrodes which in turn aids in the ignition of the illuminable gas cells of the display panel.

2. The device of claim 1 wherein said wire is comprised of nickel 63.

3. The device of claim 2 wherein said radioactive wire is of a diameter smaller than the chamber space between the pilot electrodes and wherein a holding means is provided to position said wire in said chamber.

4. The device of claim 3 wherein said holding means is comprised of a bow in the said radioactive wire, said wire in contact with each of the interior surfaces of said panel, said bow resulting in friction forces between said wire and each of said interior surfaces to hold said wire in position. 

1. In a plasma display device comprising a panel with an illuminable gas sealed in a chamber between two substantially transparent flat plates, said chamber containing a multiplicity of light emitting cells wherein each cell is formed at a crossover point of spaced orthogonal conductors, such that the gas in the region of each coordinate intersection of said conductors may be fired in response to a firing potential difference applied to said orthogonal conductors, the improvement comprising a pair of pilot electrodes one of which is disposed on the interior surface of one of said flat plates, the other of which is placed on the interior surface of the other of said flat plates, and a radioactive wire located within the chamber between the pilot electrodes, whereby the radiation from said wire aids the ionization of gas in the region of said pilot electrodes which in turn aids in the ignition of the illuminable gas cells of the display panel.
 2. The device of claim 1 wherein said wire is comprised of nickel
 63. 3. The device of claim 2 wherein said radioactive wire is of a diameter smaller than the chamber space between the pilot electrodes and wherein a holding means is provided to position said wire in said chamber.
 4. The device of claim 3 wherein said holding means is comprised of a bow in the said radioactive wire, said wire in contact with each of the interior surfaces of said panel, said bow resulting in friction forces between said wire and each of said interior surfaces to hold said wire in position. 